Multipath / SAN

1. Install device-mapper-multipath rpm.

2. Edit the multipath.conf configuration file:

• comment out the default blacklist 
• change any of the existing defaults as needed 
• save the configuration file 

3. Start the multipath daemons.

4. Create the multipath device with the multipath command.

SUSE: The /etc/multipath.conf file does not exist unless you create it.



file contains a sample /etc/multipath.conf file that you can use as a guide for multipath settings. See


for a template with extensive comments for each of the attributes and their options.

modprobe dm-multipath service multipathd start

multipath -v2 

The multipath -v2 command prints out multipathed paths that show which devices are multipathed.

If the command does not print anything out, ensure that all SAN connections are set up properly and the system is multipathed.

multipath -l 

show multipath topology (sysfs and DM info) multipath -ll show multipath topology (maximum info) chkconfig multipathd on blacklist { wwid SIBM-ESXSST336732LCF3ET0EP0Q000072428BX1 name SBIM* wird über den Befehl “multipath -v2” ausgelesen. Durch hinzufügen in die Blacklist wird das Divice nicht mehr gelistet } oder blacklist { device { vendor “IBM” product “3S42” #DS4200 Product 10 } device { vendor “HP” product “*” } } dann: service multipathd reload example multipath section: multipaths { multipath { wwid 3600508b4000156d70001200000b0000 alias yellow path_grouping_policy multibus path_checker readsector0 path_selector “round-robin 0” failback manual rr_weight priorities no_path_retry 5 } multipath { wwid 1DEC_321816758474 alias red rr_weight priorities } } dann: multipath -F flush all multipath device maps multipath -v2 show vervose mit level 2 identify devices: cat /sys/block/sda/device/vendor cat /sys/block/sda/device/model WICHTIG (redhat/centos): /usr/share/doc/device-mapper-multipath-0.4.7/multipath.conf.defaults /usr/share/doc/device-mapper-multipath-0.4.7/multipath.conf.annotated —>zeigt device info fuer /etc/multipath.conf example devices: devices { device { vendor “HP” product “OPEN-V.” getuid_callout ”/sbin/scsi_id -g -u -p0x80 -s /block/%n” } } The multipathd interactive console can be used to troubleshoot problems you may be having with your system. For example, the following command sequence displays the multipath configuration, including the defaults, before exiting the console. multipathd -k multipath konsole »show config For example, the following command sequence displays the multipath configuration, including the defaults ctrl+D multipathd -k > > reconfigure The following command sequence ensures that multipath has picked up any changes to the multipath.conf, > > CTRL-D multipathd -k Use the following command sequence to ensure that the path checker is working properly. > > show paths > > CTRL-D devices mounten:

1. filesystem erstellen mit mkfs 2. mounten (e.g) siehe “ll /dev/mpath” und auf gelinktes device mounten

mount /dev/dm-2 /mnt/tmp


           	vendor                  "COMPAQ"
            	product                 "HSV111 (C)COMPAQ"
	        getuid_callout          "/sbin/scsi_id -g -u -s"
            	prio_callout            "/sbin/mpath_prio_alua %d"    
           	features                "0"
          	hardware_handler        "0"
            	path_grouping_policy    multibus
	        failback                immediate
            	prio_callout            "/sbin/mpath_prio_alua %d"      
             	path_checker            tur
             	no_path_retry           60 

For each path group:

\_ scheduling_policy [path_group_priority_if_known][path_group_status_if_known]

For each path:

\_ host:channel:id:lun devnode major:minor [path_status][dm_status_if_known] 
linux/multipathing.txt · Last modified: 2017/12/09 01:19 (external edit)
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